"Change", reads one of the slogans raised by Bulgarian youth during their "Anonymous" protest in downtown Sofia that drew an unexpectedly high turnout. Photo by BGNES

Several thousand Bulgarian youngsters have staged a mass anti-government rally in downtown Sofia demanding an end to the rule of Prime MinisterBoyko Borisov and the GERB party, while shouting other anti-etstablishment slogans as well.

The protest rally in the center of the Bulgarian capital Monday night was organized through the social media by the Bulgarian unit of the Anonymoushacktivists, on the occassion of the Global Day of Protests declared by the Anonymous, and attracted a surprisingly high turnout.

The thousands of protesters made it clear they aim at destroying the "45+23" status quo and the political model in Bulgaria, referring to the 45-year rule of the Bulgarian Communist Party regime (1945-1989), and the post-communist period after that (1989-2012).

Many of the protesters wore the famous "Anonymous" masks but still showed their faces; their main slogan was "Down with GERB", referring to Bulgaria's ruling center-right party, which has enjoyed relatively high popularity until recently thanks largely to the image of Prime MinisterBoyko Borisov, who, however, has started to rapidly lose public approval ground in the recent months.

Several protesters from Bulgaria's "Anonymous" rally have been arrested, according to a report of the BGNES news agency.

Many of the protesters chanted, "Bulgaria, Wake Up!", "For Bulgaria", "Mafia", the popular slogan in support of Bulgaria's national football team, "Bulgari – Yunatsi" ("Bulgarian Heroes"), "You can shear us but when you skin us, who's gonna be paying you?", as well as indecent phrases directed at Prime MinisterBoyko Borisov, including calling him a "bitch" and "mutra" - the word used to describe the stereotypical Bulgarian former sportsmen-turned-gangsters who formed the backbone of Bulgaria's monstrous organized crime organizations in the 1990s.

An apparently sarcastic banner, among many others held by the protesters, showed Bulgarian and international public figures depicting them as fake revivalists of the Bulgarian nation – including current Prime MinisterBoyko Borisov, former Prime Minister Ivan Kostov, former PM and former Tsar Simeon Saxe-Coburg, mafia boss Zlatomir Ivanov, aka Zlatko Baretata, international tycoon George Soros.

The protesters could even be heard chanting, "Liberty or Death", the liberation slogan of the Bulgarian freedom-fighters against the Ottoman Empire in the 19th century.

As the police initially blocked their attempt to reach the Parliament building in downtown Sofia, they managed to circumvent the police blockade and even broke one of the windows of the Parliament building – in a reminiscence of the violent mass protests in January-February 1997 that brought down a notorious Socialist Party Cabinet.

This led the local police to call up heavily armored gendarmerie units who formed a protective cordon around the Parliament. The protesters met the gendarmerie with applause, and kept chanting, "The state is ours!", and "Down with bTV!" - referring to Bulgaria's largest private TV channel bTV, which is widely seen as staunchly pro-government, and has become highly unpopular with many young Bulgarians, especially in the social media, for showing a large number of Turkish soap operas – deemed a tool for gaining geopolitical influence by Bulgaria's neighbor.

The protest rally dispersed after several warnings by the gendarmerie and police that the protesters did not have a permission to stage a demonstration where they did. Some of them left with calls for a new protest the following night.

In addition to the mass rally in Sofia, the Anonymous managed to organize protests in the Bulgarian sea city of Varna where some 100 protesters raised slogans that "GERB Is Killing Bulgaria", and the southwestern city of Blagoevgrad where the dozens of protesters included an elderly man with a banner stating that police officers killed his son on July 27, 2008, and that the police and prosecutors have been covering up the evidence.

In the southern city of Stara Zagora, the "Anonymous" rally failed, with police officers being the only ones on the spot.

Their stated aim of the protesting Bulgarian youth was, on the Global Day of Protests declared by the Anonymoushackers, to amass the largest protest crowd in Europe in order to be able to change Bulgaria's social order.